1. Field of the Invention
The present invention generally relates to a battery operated electric tool.
2. Description of the Related Art
Generally, a portable electric device such as a lap top computer and a portable electric tool includes a battery pack capable of being charged in order to receive power required in a corresponding device. The battery pack includes a plurality of battery cells, a protect device preventing over-charge or over-discharge of each battery cell and a battery management unit (BMU), and the like.
The above information disclosed in this Related Art section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.